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O: Fachverband Oberflächenphysik

O 108: Electron-Driven Processes at Surfaces and Interfaces

O 108.11: Vortrag

Donnerstag, 19. März 2020, 17:30–17:45, TRE Ma

Coherent vibrational control of the Peierls transition in atomic Indium wires on Si(111) — •Jan Gerrit Horstmann, Hannes Böckmann, Bareld Wit, Felix Kurtz, Gero Storeck, and Claus Ropers — IV. Physical Institute, University of Göttingen, Friedrich-Hund-Platz 1, Germany

Exerting active optical control over solids by harnessing the energy stored in the electronic, lattice or spin degrees of freedom is a key objective of ultrafast science. In femtochemistry, the coherences in the electronic and vibrational states of molecules are already employed to steer reactions towards states or products far from equilibrium. However, a transfer of this concept to solids is complicated, e.g. due to a high electronic and vibrational density of states. In this respect, low-dimensional and strongly correlated systems represent a promising intermediate between molecules and solids, with phase transitions assuming the role of a "reaction". Here, we report coherent vibrational control over the phase transition in a quasi-one-dimensional Peierls insulator by manipulating the vibrational amplitudes of decisive lattice modes. Specifically, we employ an optical double-pulse excitation scheme and monitor the structural transformation between the insulating (8×2) and the metallic (4×1) phase of atomic indium wires on Si(111) by ultrafast low-energy electron diffraction (ULEED). An analysis of the delay-dependent phase transition efficiency proves the distinct roles of specific phonon modes for the transition and provides insight into the underlying control mechanisms and structural pathways.